Clinical meaning
The clinician applies a systematic algorithm to evaluate acute abdominal pain, differentiating surgical emergencies requiring immediate intervention from medical conditions amenable to conservative management. Surgical emergencies include: perforated viscus (sudden-onset severe pain, peritoneal signs, free air on upright chest or left lateral decubitus X-ray -- Rigler sign on CT), bowel obstruction (small bowel: colicky periumbilical pain, vomiting, distension, high-pitched tinkling bowel sounds, air-fluid levels on abdominal X-ray; large bowel: gradual distension, constipation, less vomiting), mesenteric ischemia (pain out of proportion to examination in a patient with atrial fibrillation or vascular disease -- arterial lactate elevation, CT angiography showing mesenteric vessel occlusion), ruptured abdominal aortic aneurysm (sudden tearing pain radiating to the back, hypotension, pulsatile abdominal mass -- do NOT delay for imaging if hemodynamically unstable), and ectopic pregnancy rupture (positive beta-hCG, acute pelvic pain, peritoneal signs, free fluid on FAST ultrasound). The clinician applies location-based differential diagnosis: right upper quadrant (cholecystitis, hepatitis, pneumonia, pulmonary embolism), epigastric (peptic ulcer, pancreatitis, GERD, MI), left upper quadrant (splenic pathology, gastric ulcer), right lower quadrant (appendicitis, ovarian pathology, ectopic pregnancy, Meckel diverticulitis), suprapubic (UTI,...